A Compact Electromagnetic Vibration Harvesting System with High Performance Interface Electronics

A compact vibration-based electromagnetic (EM) energy harvesting system utilizing high performance interface electronics, has been presented. The energy harvester module consists of an AA-battery sized cylinder tube with an external coil winding, a fixed magnet at the bottom of the tube, and a free magnet inside. The transducer is able to operate at low external vibration frequencies between 9.5 and 12 Hz. The generated AC voltage is converted to DC using a custom rectifier circuit that utilizes a gate cross coupled (GCC) input stage. This decreases the effective threshold voltage of the utilized diodes, while increasing the DC output power delivered to the load. The autonomous system, composed of an EM energy harvester module and a 0.35 μm CMOS IC, delivers 11.6 μW power to a 41 μA load at an external vibration frequency of 12 Hz. The volume of the total system is 4.5 cm3, and the overall system power density is 2.6 μW/cm3.